A timeline of events leading up to 2013 Boston Marathon bombing and the legal aftermath

FILE - In this Monday, April 15, 2013 file photo, the elite men start the 117th running of the Boston Marathon in Hopkinton, Mass. (AP Photo/Stew Milne) (The Associated Press)

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FILE - In this image from video provided by WBZ TV, a bomb explodes near the finish line of the Boston Marathon in Boston on Monday, April 15, 2013. On Friday, May 15, 2015, Dzhokhar Tsarnaev was sentenced to death by lethal injection for the terror attack. (AP Photo/WBZ-TV) MANDATORY CREDIT: WBZ-TV (The Associated Press)

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FILE - In this Monday, April 15, 2013 file photo, medical workers aid injured people at the finish line of the 2013 Boston Marathon following an explosion in Boston. (AP Photo/Charles Krupa) (The Associated Press)

A timeline of events related to the Boston Marathon bombing, which killed three people and injured 260 others on April 15, 2013. A federal jury on Friday sentenced Dzhokhar Tsarnaev to death.

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March 2011: Russian FSB intelligence security service gives FBI information that Tamerlan Tsarnaev, of Cambridge, Massachusetts, is a follower of radical Islam.

Sept. 12, 2011: Bodies of three men are found in Waltham, Massachusetts, with their throats slit and marijuana sprinkled over them.

Late 2011: U.S. officials add the Tsarnaevs' mother to a federal terrorism database after Russia contacts CIA with concerns they were religious militants about to travel to Russia. She later says she has no links to terrorism.

January 2012: Tamerlan arrives in Russia, where he spends time in two predominantly Muslim provinces, Dagestan and Chechnya.

July 2012: Officials in Dagestan say Tamerlan applies for a new passport but never picks it up. Russian officials say they have him under surveillance but lose track of him after the death of a Canadian man who had joined an Islamic insurgency in the region.

July 17, 2012: Tamerlan returns to U.S.

November 2012: Islamic Society of Boston Cultural Center in Cambridge says Tamerlan has an outburst that interrupts a sermon about it being acceptable for Muslims to celebrate American holidays.

January 2013: Islamic Society says Tamerlan has a second outburst after a sermon that includes praise for the Rev. Martin Luther King Jr.

April 15, 2013: Bombs go off at the finish line of the Boston Marathon.

April 16, 2013: Federal agents say the bombs were made from pressure cookers packed with explosives, nails and other shrapnel, but they still don't know who detonated them or why.

April 17, 2013: President Barack Obama signs emergency declaration for Massachusetts and orders federal aid to supplement local response.

April 18, 2013: Investigators release photos and video of two suspects and ask for public's help identifying them. Later that night, Massachusetts Institute of Technology police officer Sean Collier is shot to death in his cruiser by Tamerlan and Dzhokhar Tsarnaev. They steal an SUV at gunpoint from a Cambridge gas station. The driver is held for about a half-hour, then released unharmed.

April 19, 2013: Tsarnaevs have an early morning gunbattle with authorities who have tracked them to Watertown. Tamerlan, who is run over by his younger brother, dies. Dzhokhar escapes, and at around 6 a.m., authorities tell residents of Boston and surrounding communities to stay indoors. All mass transit is shut down. That order is lifted around 6:30 p.m., just before authorities trace Dzhokhar to a Watertown backyard, where he is found hiding in a boat and taken into custody.

April 22, 2013: Dzhokhar Tsarnaev, injured in the shootout, is charged in his hospital room with using and conspiring to use a weapon of mass destruction.

April 30, 2013: Two friends of Dzhokhar's are charged with attempting to destroy evidence by disposing of a backpack and laptop computer taken from his room after they found he was a suspect in the bombing. Another is charged with lying to investigators.

May 9, 2013: Tamerlan Tsarnaev is secretly buried in Virginia after a weeklong search for a cemetery willing to take the body.

May 22, 2013: An FBI agent in Orlando, Florida, fatally shoots Ibragim Todashev, a friend of Tamerlan's, after he lunges at law enforcement officials questioning him about the Waltham killings. Officials say that before he died, he had agreed to give a statement about his involvement.

July 23, 2013: Marc Fucarile is the last survivor of the bombings to leave the hospital.

Jan. 30, 2014: Prosecutors announce they will seek the death penalty against Dzhokhar.

April 15, 2014: Ceremonies and events mark the anniversary of the attacks.

April 21, 2014: The 2014 Boston Marathon features a field of 36,000 runners, 9,000 more than 2013 and the second-biggest field in history.

May 30, 2014: Khairullozhon Matanov, 23, of Quincy, is arrested on charges of obstructing the investigation by deleting information from his computer and lying to investigators.

June 18, 2014: Tsarnaev's lawyers file first of several requests to move the trial to Washington, D.C.

July 21, 2014: Azamat Tazhayakov, a college friend of Dzhokhar's, is convicted of obstruction of justice and conspiracy for agreeing with another friend to get rid of a backpack and disabled fireworks they took from his dorm room three days after the attack.

July 22, 2014: Stephen Silva, believed to have provided the gun used by the Tsarnaevs to kill Collier, is arrested on drug and weapons charges.